Apparatus for extruding wide metal sheets



J ne 22, 1954 K. F. BRAEUNINGER 2,681,134

APPARATUS FOR EXTRUDING WIDE METAL SHEETS 3 Sheets-Sheet l Filed Jan. 16, 1951 E51. fi E- IN V EN TOR.

KHEL EBEHEU l/VGEB HL M14,

HTTOENEYS June 22, 195 K. F. 'BRAEUNINGER 2,

APPARATUS FOR EXTRUDING WIDE METAL SHEETS Filed Jan. 16, 1951 3 Sheets-sheaf; 3

I [U A Mi 3: I: n ah IN VE N R- ifi' Tn' ml I KEEL 56050 E I H 4014,

Patented June 22, 1954 APPARATUS FOR EXTRUDING WIDE METAL SHEETS Karl F. Braeuninger, Gundernhausen (Darnstadt), Germany, assignor to the United States of America as the Air Force represented by the Secretary of Application January 16, 1951, Serial No. 206,285 3 Claims. (Cl. 207-17) (Granted under Title ss u. s. Code (1952),

sec. 26

The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to a method of extruding thin and wide ribbed metal sheets and particularly to the construction of extrusion dies capable of Carrying out the method.

In order to produce as wide a sheet as possible in a given size extrusion press resort may be had to first producing a sheet of U-shaped cross section then flattening out the U to form a flat sheet of substantially double the width that would normally be produced in the press.

But while the foregoing procedure is highly satisfactory in that it produces a wide fiat sheet in a die which is much smaller than the width of the sheet, considerable difficulty is encountered in designing and constructing a die which will stand the strains incident to extruding metal into a U-shaped cross section wherein the space between the legs of the U is small relative to their length, in which case parts of the die overhan in cantilever fashion to such an extent that they are unstable at the free ends and for that reason incapable of producing accurate sections.

Experiments have shown that most of the aluminum and magnesium alloys when in a plastic state and properly confined and subjected to appropriate pressure will divide and flow over the sides of a streamlined body. Moreover, it has been demonstrated that, when past this streamlined profile, the metals flow back together and produce an excellent weld.

It is therefore an object of the invention to provide a die capable of extruding profiles of U shape in which the bars of the U are close together relative to their length, yet so brace the free ends of the cantilever portions of the die as to maintain a high degree of accuracy in the product.

I attain this and other objects in the structure hereinafter described, reference being had to the drawings, wherein:

Fig. 1 is a top plan view of the one-piece die.

Fig. 2 is a cross section taken on the line 2-2 of Fig. 1 showing one of the bridges which supports a weaker portion of the die.

Fig. 3 is across section taken at 33 of Fig. 2 through the die proper.

Fig. 4 is a cross section taken at 44 of Fig. 1 showing the streamline contour of the bridge.

Fig. 5 is an axial section through the press which is used to contain the die shown in Figs.

2 l to 3 and to extrude a metal billet therethr-ough.

Fig. 6 is a schematic view showing how the extruded metal divides and flows around the bridge and welds again.

Fig. 7 illustrates how the residue is removed by the trimmer Of the press.

Fig. 8 shows that the grain at the place where the weld occurred is improved.

Fig. 9 shows a modified cross section whereby a still wider sheet may be extruded in a given press.

Like reference characters refer to like parts throughout the several views.

Referring now to the drawings and more particularly to Fig. 3, let it be assumed that a section of sheet metal of width W-W and thickness T is to be extruded. If the available press and its die [0 will not accommodate an extruding slot ll of the desired width W-W and thickness T in one plane, the sheet may be extruded in U shape, as shown, and flattened thereafter.

It is, however, extremely diificult to extrude U-shaped profiles with any appreciable degree of accuracy, particularly where the width or thickness at D is small relative to the length L, since in this case the tongue l2 of the die is: a cantilever supported only at the one end E as shown, which leaves the end D otherwise unsupported. Considering that the pressure on the outer end D of the tongue I 2 may be as much as 180,000 p. s. i. the deflection of the tongue at D, which may be either in the direction of the pressure or transverse thereto, is such as to preclude the I possibility of making accurate wall thicknesses in the finished product.

In order to minimize deflection 0f the end D of the tongue 12 during extrusion of the U- shaped profile, a bridge I 4 (see Figs. 1, 2 and 4) is provided for connecting the free end D of the tongue 12 to a solid portion 16 of the die. This bridge I4 is an integral part of the die it proper and constitutes an important feature of the invention. It consists of 2. lug extending integrally upward from the top surface of the die 10, the lug having a transverse thickness somewhat less than the dimension D of the tongue l2, and has an underpass so contoured as to leave a streamlined connecting portion above the underpass.

This streamlined contour is that part of the bridge which remains after forming bellmouthed tunnels [8, Figs. 1, 2 and 4, in the sides of the bridge at the juncture between the bridge and the face of the die which communicate with the extruding slot H, whereby that portion of the extruding slot H which falls under the bridge M will be supplied by that portion of the billet prises I i, the die H3 and the rarn26 are'concentrically positioned.

' (see Figs. land 5).

tearing apart at of the bridge cross section is therefore considered an important feature of theinvention. .Fig. 6 shows how the billet metal f4 flows down over the sides of the bridge l4 and lLTll'tES and welds in the underpass of the bridge. (See also Fig. 4.)

Moreover, repeated tests have demonstrated that the grain in the extruded metal at th'e' weld is improved rather than injured (see Fig. 8).

The die it hereinbefore shown and described is set up in a conventional extrusion-press-sche matically shown at in Fig. 5. This press coma billet container 12-2 within which the billet The die it is supportedby the back-up piece 28 which is in turn held in the die holder 30. A

locking member 32 is provided for'retaining the parts I0, 28, 39 in the position shown pending, extrusion.

Ihe extrusion operation is carried out substantially as follows:

The die it, back-up piece 28 and die holder are assembled as shown in concentric relation "with the press .20 and billet container 22 and the locking member 32 entered through its slot in the press. The ram 26 is withdrawn to the left and a heated billet 24 is placed in the container 22. The ram 26 is now moved toward the right, forcing the billet 24 over the sides of the bridge i4 and through the tunnels l8 and through such portion of the extruding slot I l as lies under the bridge I4, the remainder of the extruding slot H receiving metal directly from the billet 2d Extrusion now continues until the end 34 of the ram 26 is about on the line FF.

The locking member 32 is now withdrawn whereupon the ram 26 may be moved rightwise, thereby pushing the die Hi, back-up piece 28 and die holder 30 rightwise completely clear of the billet container. 22. The ram 26 is now moved leftwise away from the waste slug 36 whereupon the die and slug appear as in Fig. 7.

Fig. 7 shows the die It with the waste slug 36 still attached, but with the transverse trimmer cutter 38, which is a part of every extrusion press, in position for removing the waste slug from the die. By moving the cutter 38, Fig. 7, in the direction of the arrow 49, the waste slug rides up the incline '42 of the bridge 14 thereby G, Figs. 4 and 7, and spreading the portion of the waste which is in the tunnels i 8, that is, moving the waste slug 36, Fig. 7, along the incline 42 of the bridge 36 will not only tear apart the small slugs in the tunnels but will spread them apart, due to the streamlined shape of the bridge 14. The die [4 is therefore selfcleaning, a 'valuable feature of the invention.

Moreover, thepresence of a weld, where consecutive charges meet, is avoided, such conditions, as is well known, being conducive to unsoundness. The incline 42 is also animportant part of 'the invention. I r In the foregoing I have shown equipment and a method whereby wider sheets ofmetal maybe extruded in a given size die by making the extrusion slot H in U shape instead of straight, then flattening the extruded U to compose a uniplanar sheet. It will be readily understood, however, that this method may be extended to compose still'wider sheets by making the extrusion .slot in an S shape as seen in Fig. 9. Still wider sheets may be extruded in the same size die by .providingan extruding slot having a still greater number of convolutions than shown in Fig. 9 if the dimension D is made much narrower relative .to'th'edimension'L than shown in Fig. 9. Additionally the greater number of convolutions will call for a greater number of bridges in the die.

The invention, moreover, lends itself to the making of ribbed-sheets, the ribsv 44 being integral with the sheet and all on one side thereof as seen'in Fig. 9, whereby, when the convolutions are flattened out,-a"ribbed sheet is provided which, it is contemplated, will be extensively used for making the skins of aircraft.

=Having described-my invention, I claim:

1. Apparatus for producing thin wide metal sheets by extrusion comprising a die member having a base portion including a thin elongated U- shaped slot therethrough providing a tongue member centrally'thereof, a bridge member integral with said base portion and connecting the tongue member with the opposed base portion'at the other side'of the slot at its point of greatest convexity, the bridge member being spaced from said base portion above the slot and having an inclined surface at one-end thereofto facilitate the separation of the waste slug from a billet being extruded through the die member and over the bridge member.

2. Apparatus for producing thin wide metal sheets by extrusion comprising a base member having anarrow elongated U-shaped extrusion slot therethrough providing a narrow tongue member therebetween, a streamlined bridge member extending from said base member and integral therewith connecting the tongue member andanopposed portion of the base member across the slot atits point of greatest convexity, the portion of the bridge member across the slot being spaced from the base member whereby metal flow past the bridge'member produces a weld thereunder in the metal extrudedthrough the slot'at its point of greatest convexity.

3.-Appara'tus for extruding thin wide metal sheets comprising a base member having a narrow -U -shaped slot 'therethrough providing a tongue portion'thereof surrounded by said U- shaped slot, a streamlined bridge member bridging the slotat its point of greatest convexity extending from the tongue portion to the opposed portion of the base member and integral there- 'with whereby a U-shaped member extruded thereby will producea Wide metal sheet.

References Cited in the file of this p tent UNITED STATES PATENTS 

